Car alarms often include an auxiliary or accessory channel output that can be used to activate an accessory by operation of the alarm system remote control. Although one accessory may be sufficient for some individuals, other individuals may wish to selectively operate a desired accessory selected from a group consisting of two or more accessory devices. For these individuals it would of course be desirable to have an accessory channel expander for a vehicle alarm that could be connected to the single auxiliary or accessory channel output of the vehicle alarm and that included a mechanism for using that remote control activated single auxiliary or accessory channel output to select the desired accessory from a group of two or more accessories. It would also be desirable to have an accessory channel expander for a vehicle alarm that included a scrolling mechanism that scrolled or stepped through the possible channels and allowed the user to use the remote control activated single auxiliary or accessory channel output of the alarm system to selectively activate the desired accessory channel through operation of the alarm remote control.